San Francisco, CA (Sports Network) - Brandon Belt drove in three runs, Hector Sanchez registered a pair of hits and two RBI and Melky Cabrera scored twice as San Francisco Giants held on for an 8-6 victory over the Oakland Athletics in the opener of a three-game interleague series on Friday.

Barry Zito (3-1) surrendered four runs on five hits and a walk in 5 1/3 innings for the Giants, who had a seven-run lead at one point before clinging on for the win over the last few frames.

"We've been putting up some runs this last week," said Zito. "These guys that we got going in the lineup, they're getting it done."

San Francisco has won each of its last 10 home games against the A's.

Josh Donaldson smacked three hits, including a solo home run, to go with five RBI for Oakland, which has dropped four of its last six contests.

Jarrod Parker (1-2) lasted just two innings and allowed six runs on four hits and a quartet of walks.

The A's trailed 8-1 following four innings of play, but charged back after tallying a run in the fifth and four more in the sixth.

Donaldson lined an RBI double in the fifth while Jemile Weeks began the sixth with a triple to right-center before scoring on Cliff Pennington's base hit to left-center. With the bags full four batters later, Donaldson cracked a bases-clearing double into the left-center field gap to cut the deficit to 8-6.

But the back-end of San Francisco's bullpen secured the win by tossing three solid frames to close the contest.

Jeremy Affeldt and Sergio Romo each fanned two in a 1-2-3 seventh and eight, respectively, while Santiago Casilla notched his 10th save of the year after pitching around a single and an error in the ninth.

"You always want to keep battling and keep fighting. We did that all the way through the ninth inning," Oakland manager Bob Melvin said.

Earlier, the Giants struck first with a pair of runs in the second inning as Belt and Joaquin Arias recorded an RBI single and sacrifice fly, respectively.

The Athletics cut the deficit to 2-1 in the third frame on Donaldson's solo shot over the wall in left-center, but the Giants retaliated with four runs in the bottom half.

Brandon Crawford laced an RBI double into the right-center field gap and Sanchez's sacrifice fly to center was sandwiched in between a pair of bases-loaded walks by Belt and Zito, which pushed the Giants' margin to 6-1.

San Francisco plated two more for an 8-1 lead in the fourth inning on Belt's sacrifice fly to center and Sanchez's RBI double into right-center.

Game Notes

The Giants have won five of their last seven games...San Francisco has gone 124-116 in interleague play since it began in 1997, the fourth highest winning percentage in the NL...Of the 20 games at At&T Park this season, 19 have been decided by three-runs-or-less.